There are some prior art methods for detecting and identifying hidden nuclear materials. The most notable technique utilizes a gamma-ray spectrometer to measure the gamma-ray spectrum, and the system consists of a high-sensitivity gamma-ray detector made of high purity germanium (or lithium or other material) and a multi-channel analyzer. For a relatively high-sensitivity gamma-ray spectrometer, the gamma-ray detector is typically cooled by a cryogenic liquid (mostly liquid nitrogen), and the detector must be carefully handled since it can be easily damaged. In addition, the spectrometer is expensive to procure and operate as it constantly requires cryogenic liquid, and it is too delicate to operate by a layperson. Furthermore, the gamma-ray spectrometer is not sensitive enough to detect an isotope at a long distance.
In another prior art method, a system uses a single chamber to detect a nuclear material; however, this method does not allow the identification of the type of nuclear material detected.
Other techniques of detecting and identifying hidden nuclear material include the acoustic technique, the thermal imaging technique, and the air-fluorescence technique. Each of these techniques has been investigated by many other research groups, and all have proved to be unreliable. In addition, active detection techniques, such as active neutron techniques and the use of high-energy electromagnetic showers, including high-energy protons and active gamma techniques, are not safe to operate and can be very expensive.
Accordingly, there remains a need in the art for a system and method of detecting and identifying remote nuclear material at a standoff distance, which is more accurate than prior art systems and easier and less expensive to operate.